1. Field of the Invention
This invention relates to a cable connection structure and a cable connection method for connecting a center conductor of a cable to an electrode formed on a printed circuit board etc.
2. Description of the Related Art
In recent years, reduction in size and weight of various terminal devices, such as, e.g., notebook computer or cellular phone, is demanded in the field of electrical and electronic equipment. Those terminal devices have a structure in which, e.g., an upper housing provided with a liquid crystal display is coupled and fixed to a lower housing provided with a controller via a hinge portion which is three-dimensionally movable, and operability and functionality thereof have been enhanced.
Such terminal devices need to transmit and receive an electric signal between the upper and lower housings via the three-dimensionally movable hinge portion. Therefore, plural cable conductors each of which has a center conductor having a substantially circular cross section formed of a twisted wire or a single wire and an insulator coating an outer periphery thereof, as is a three-dimensionally movable cable e.g., a coaxial cable, are arranged passing through the hinge portion.
Generally, for connecting the plural cable conductors to printed circuit boards which are respectively arranged in two housings, the cable conductors are each soldered and connected to plural connection electrodes formed on the printed circuit boards, or the cable conductors are soldered to each of plural electrode terminals of a connector and are connected to a printed circuit board through the connector.
In the meantime, there is a tendency to reduce an outer diameter of a cable conductor or to narrow an arrangement pitch distance of connection electrodes of a printed circuit board or electrode terminals of a connector to be connected to a cable conductor according as the terminal device becomes highly functional, multi-functional and high density in packaging etc. Accordingly, a coaxial cable used is a micro coaxial cable with, e.g., an outer diameter of about 0.2 mm to 0.15 mm, which is very thin. The plural connection electrodes of the printed circuit board or the electrode terminals of the connector to be connected to the micro coaxial cable are used by being arrayed at a pitch of, e.g., 0.25 mm as an electrode array.
Generally, plural micro coaxial cables as described above are arrayed at a predetermined pitch, are sandwiched and laminated with an adhesive tape on both surfaces, and are used in a flat form. When the plural micro coaxial cables are connected to, e.g., plural connection electrodes of a printed circuit board which are arrayed at an extremely narrow pitch, positions of the micro coaxial cables with respect to the connection electrodes are aligned manually by using, e.g., a microscope, etc., since each of the micro coaxial cables is very thin and flexible, and work for connecting the micro coaxial cable to the connection electrode is carried out using a sharp soldering iron having a tip diameter of 0.2 mm, etc.
In the entire work of connecting such a micro coaxial cable, it is extremely difficult especially to align the position of the micro coaxial cable on the connection electrode. Therefore, various methods of connecting a micro coaxial cable have been proposed to facilitate positioning to a board as an object to be connected and connection work of micro coaxial cable.
One example of the methods of connecting a micro coaxial cable is proposed in, e.g., JP-A-2002-95129 (hereinafter referred to as “patent document 1”). In the method of connecting a micro coaxial cable described in the patent document 1, center conductors of plural micro coaxial cables are fitted to plural cable positioning grooves formed on a grooved heat ray transmitting member (hereinafter referred to as “cable positioning jig”), are pressed and fixed to a solder formed on a pad of a board after positioning and alignment, and are solder-connected to the pad by supplying a heat ray via the cable positioning jig.
Another example of the methods of connecting a micro coaxial cable is proposed in, e.g., JP-A 2008-251252 (hereinafter referred to as “patent document 2”). In the method of connecting a micro coaxial cable described in the patent document 2, a wire solder is placed on center conductors of plural micro coaxial cables which are arrayed so as to correspond to plural electrode terminals of a connector, the center conductors are fitted to plural cable positioning grooves formed on a cable positioning member (hereinafter referred to as “cable positioning jig”) to position and align with respect to the electrode terminals of the connector, and are solder-connected thereto via the wire solder by pressing and heating using a heater chip.